1. Field of the Invention
This invention relates to fiber reinforced polymer (FRP), and more specifically, to lightweight fiber reinforced polymer composite decks for structural support systems and to a method of manufacturing said FRP composite decks. The lightweight FRP composite decks are composed of reinforced fibers and matrix resin, configured for infrastructure and constructed facilities such as elevated highway structures and wall and decking systems.
2. Related Art
Structural panels are continually needed in constructing and repairing walls, floors, decking, bridges, roofs, and the like. In the prior art, conventional construction materials, e.g., steel, concrete, and wood, are used for high performance deck and wall structures because such materials typically have a high load bearing capacity.
There are several disadvantages associated with using such conventional construction materials in structural panels. First, such structural panels have a short service life in that they degrade over time: steel panels corrode, concrete panels spall, and wood panels rot. Second, such structural panels tend to be very heavy in order to achieve the required load bearing capacity for the specific application. Third, such structural panels require a long time for creation and erection because they are typically built and installed on site.
To accommodate some of the disadvantages with conventional construction materials, the prior art includes fiber reinforced polymer (FRP) composite materials made with a honeycomb core and an outer skin. In addition, panels made of conventional FRP composite materials have lineal profiles mainly reinforced with continuous fibers in the axial direction.
There are several disadvantages associated with using such conventional FRP materials in structural panels. First, although conventional FRP composite materials are lightweight, they lack the required load-bearing capacity to handle high performance deck and wall structures. Therefore, conventional FRP composite materials are used only for light duty floor systems and building panels. Second, conventional FRP composite panels often develop moisture ingress and resin-dominated failure with respect to the honeycomb core and an outer skin. Third, the lineal profile and use of continuous fibers in the axial direction result in a reduced load bearing capacity.
Therefore, there is a need for a FRP composite panel that is lightweight, yet has a high load rating due to high strength to weight ratio. There is a further need for a FRP composite panel that has a long service life due to its resistance to corrosion. There is still a further need for a FRP composite panel that is easy and quick to erect and become operational.
There is also a need for a FRP composite deck system that is lightweight, yet can withstand the heavy loads associated with highway bridges and decking systems. The FRP composite deck systems must also have a long service life and be prefabricated to allow for easy and quick installation.
The present invention solves the problems associated with conventional structural panels by providing a fiber reinforced polymer (FRP) composite panel. A FRP composite panel comprises a plurality of components, joined through a shear key system that provides an extensive bonding surface and a mechanical interlock. Each component is further comprised of a plurality of cells, each cell having four or more sides wherein at least two adjacent sides intersect at an obtuse angle, offset from ninety (90) degrees.
The fiber architecture of the components comprises multiple layers of multi-axial stitched fabrics, unidirectional rovings, woven cloth, and mats used as reinforcements. The fiber architecture develops fiber continuity between the cell components and provides adequate fiber reinforcement along main stress paths.
The cross sectional cellular shape and fiber architecture of the FRP composite panels of the present invention provide distinct advantages over the prior art. First, the FRP composite panels of the present invention provide a lightweight, strong and durable structure that will not corrode like steel, spall like concrete, or rot like wood. Therefore, the panels of the present invention have a long service life and a reduced maintenance cost due to these fatigue and corrosion resistant properties.
Second, the FRP composite panels of the present invention have enhanced load bearing and interlocking capacity as compared to conventional FRP floor systems and building panels. The high load ratings are due to the high strength to weight ratio of the panels, resulting in a panel of the present invention having 3 to 4 times the load capacity of a reinforced concrete deck with only twenty percent (20%) of the weight. Further, stiffness of an FRP composite panel in the direction perpendicular to traffic is adequate to provide the transverse load distribution to supporting beams.
Third, the fiber architecture of the present invention is reinforced with heavy multi-axial stitched fabrics, continuous rovings, woven cloth and mats resulting in superior mechanical properties as compared to existing FRP composite lineal profiles. In addition, the composite fiber architecture overcomes the problems associated to moisture ingress and resin-dominated failure observed in panels with honeycomb core and outer skins.
In a specific application of FRP composite panels of the present invention, FRP composite deck system comprise a plurality of cells having a double trapezoidal component and a hexagonal component for highway bridges and other decking applications. These components are prefabricated and joined together with an adhesive to form a modular FRP composite deck system. In addition to the extensive bonding surface, a mechanical connector may be used to increase the shear transfer capacity of the panel.
FRP composite panels of the present invention can be properly designed, fabricated, and installed very efficiently. Such FRP composite panels can be used to replace deteriorated concrete or timber decks or to build new decks. Further, such panels can be assembled with composite stiffening beams to develop an all-composite short-span bridge superstructure. Construction and replacement applications of the modular FRP composite structural panels and decks include, but are not limited to: highway bridge decks, short span highway bridge structures, pedestrian bridges, floor systems, retaining walls, pilings, waterfront piers, platforms, launch bridges, utility poles, pipes, blast resistant structures, shock absorber structures, framing structures (for tunnels, buildings, mines, and the like), and alternative comparable applications.